The present invention relates to a method of waterproofing a crimping part between a crimp terminal formed of copper family material to be fitted by engagement to a connecter housing and a core wire part which is exposed in an end part of a coated aluminum wire.
End parts of electric wires including a wire harness which is arranged in a vehicle are so constructed, in many cases, as to be equipped with crimp terminals to be fitted by engagement to a connecter housing, for facilitating connection between the electric wires and an apparatus.
Conventionally, as the crimp terminal to be fitted by engagement to the connector housing, a crimp terminal formed of copper family material which is excellent in resiliency and electrical conductivity has been widely used.
On the other hand, in recent years, the number of the electric wires contained in the wire harness tends to be increased with an increase of electronic apparatuses mounted on the vehicle, and so, for the purpose of making the wire harness lightweight, use of a coated aluminum wire of a type that a core wire formed of aluminum or aluminum alloy is covered with an insulating sheath has been required.
Under such circumstances, it is necessary to secure reliability of such a structure that the crimp terminal formed of copper family material is connected by crimping to the end part of the coated aluminum wire.
However, because metals of different kinds are contacted with each other in a crimping part where the crimp terminal formed of copper family material is connected by crimping to the end part of the coated aluminum wire, erosion is likely to occur when water adheres to the crimping part. Consequently, there is such anxiety that inconveniences such as faulty connection may be incurred by the erosion in the crimping part.
Therefore, the crimping part between the coated aluminum wire and the crimp terminal formed of copper family material must be designed as a waterproofing structure for preventing adhesion of water.
Heretofore, as the method of waterproofing the crimping part by designing the crimping part as the waterproofing structure, there has been proposed the art in which the crimping part is tight-sealed with a resin mold (see, Patent Document 1) or the art in which a heat contractive tube covered around the crimping part is contracted thereby to tight-seal the crimping part (see, Patent Document 2).    [Patent Document 1] Japanese Patent Publication Number 2001-167821 A    [Patent Document 2] Japanese Patent Publication Number 2005-268194 A
However, in case of the waterproofing methods which are disclosed in the above described Patent Documents, an outer shape of the crimping part is swelled outward by 0.1 mm or more from the outer shape of the crimp terminal, in both cases. Consequently, it becomes unable to fit the crimp terminal by engagement to the connector housing of which a clearance with respect to the crimp terminal is set to be 0.1 mm or less.
In short, in case of the crimp terminal formed of copper family material to be fitted by engagement to the connector housing, it is impossible to apply the conventional waterproofing structure to the crimping part. Moreover, because waterproofing performance of the crimping part cannot be secured, there has been such a problem that it is impossible to enhance erosion resistance of the crimping part.